Reaction of [RhCl(CO)2]2 or [RhCl(COD)]2 with o-(diphenylphosphino)benzaldehyde. Formation of hemiaminals in the subsequent reaction with dihydrazones

Article abstract of DOI:10.1016/S0022-328X(01)01381-X

[RhCl(CO)₂]₂ reacts with o-(diphenylphosphino)benzaldehyde (PCHO) to afford a monocarbonylated rhodium(I) complex containing P-monodentate PCHO, trans-[RhCl(CO)(PCHO)₂] (1) while [RhCl(COD)]₂ undergoes the oxidative addition of one PCHO, with displacement of 1,5-cyclooctadiene, and coordination of the second PCHO molecule as P-(σ-aldehyde) chelate to give [RhH(PCO)Cl(PCHO)] (2) which contains trans P-atoms. Compound 2 reacts with H₂NN=CHCH=NNH₂ (gdh) to give selectively a complex [RhH(PCO)(Pgdh)]⁺ containing a stable hemiaminal in a new tridentate ligand, Pgdh, coordinated via the imino nitrogens and the phosphorus and the atom. The reaction of Rh(COD)(gdh)Cl with PCHO gives a mixture of the hemiaminal containing compound and the hydroxyalkyl complex [Rh(PCO)(PCHOH)(gdh)]⁺ which contains trans P-atoms and is formed from precursors containing cis P-atoms. The transformation of the hemiaminal group in [RhH(PCO)(PNN)]⁺ (PNN = Pgdh or Ppvdh (pvdh, H₂NN=CHC(CH₃)=NNH₂)) into imine to give new tridentate PaNN ligands in complexes [RhH(PCO)(PaNN)]⁺ has also been studied.

Full text of DOI:10.1016/S0022-328X(01)01381-X

Journal of Organometallic Chemistry 648 (2002) 149–154
www.elsevier.com/locate/jorganchem
Reaction of [RhCl(CO)2]2 or [RhCl(COD)]2 with
o-(diphenylphosphino)benzaldehyde. Formation of hemiaminals in
the subsequent reaction with dihydrazones
Rachad El Mail, Mar´ıa A. Garralda *, Ricardo Herna´ndez, Lourdes Ibarlucea
Facultad de Qu´ımica de San Sebastia´n, Uni6ersidad del Pa´ıs Vasco, Apdo. 1072, 20080 San Sebastia´n, Spain
Received 25 July 2001; accepted 9 October 2001
Abstract
[RhCl(CO)2]2 reacts with o-(diphenylphosphino)benzaldehyde (PCHO) to afford a monocarbonylated rhodium(I) complex
containing P-monodentate PCHO, trans-[RhCl(CO)(PCHO)2] (1) while [RhCl(COD)]2 undergoes the oxidative addition of one
PCHO, with displacement of 1,5-cyclooctadiene, and coordination of the second PCHO molecule as P-(s-aldehyde) chelate to give
[RhH(PCO)Cl(PCHO)] (2) which contains trans P-atoms. Compound 2 reacts with H2NNꢀCHCHꢀNNH2 (gdh) to give selectively
a complex [RhH(PCO)(Pgdh)]+ containing a stable hemiaminal in a new tridentate ligand, Pgdh, coordinated via the imino
nitrogens and the phosphorus and the atom. The reaction of Rh(COD)(gdh)Cl with PCHO gives a mixture of the hemiaminal
containing compound and the hydroxyalkyl complex [Rh(PCO)(PCHOH)(gdh)]+ which contains trans P-atoms and is formed
from precursors containing cis P-atoms. The transformation of the hemiaminal group in [RhH(PCO)(PNN)]+ (PNN=Pgdh or
Ppvdh (pvdh, H2NNꢀCHC(CH3)ꢀNNH2)) into imine to give new tridentate PaNN ligands in complexes [RhH(PCO)(PaNN)]+
has also been studied. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Aldehydes; Oxidative-addition; Rhodium complexes; Hemiaminals
thermally unstable [IrH(PCO)Cl(COD)] that has been
proposed as model intermediate in this process [9] and
[RhCl(1,4-pentanediene)]2 reacts with 8-quinolinecar-
baldehyde (NCHO) to give an allyl compound
[RhCl(h3-1-ethyl-allyl)(NCO)]2 most likely via an acyl-
hydride diolefin intermediate [RhH(NCO)Cl(1,4-pen-
tanediene)] [10]. PCHO has been used to add
oxidatively to rhodium(I) [5], iridium(I) [9] platinum(0)
[11] or cobalt(I) [12] yielding cis acylhydride complexes
that contain acylphosphine chelates (PCO). It can also
1. Introduction
Organometallic rhodium complexes play an impor-
tant role in the transformation of many organic com-
pounds [1] and the most studied catalysts are those
containing phosphine ligands. Many transformations
involving aldehydes such as decarbonylation, hydroacy-
lation, hydrosilylation, hydrogenation or hydroformy-
lation are catalysed by rhodium complexes and may
involve oxidative addition of aldehyde to rhodium(I)
[2]. Cleavage of CꢁH bonds in aldehydes and promoted
by rhodium may lead to acylhydride species [3–6].
When the aldehyde is close to a donor atom and
chelates can be formed, the corresponding acylhydride
complexes are easily obtained [5,7] and some of them
are active catalysts in the hydroacylation of olefins
[7,8]. The reaction of [IrCl(COD)]2 with o-
(diphenylphosphino)benzaldehyde (PCHO) gives the
coordinate
as
monodentate
P-donor
as
in
[Rh(CO)(PCHO)(m-pz)]2 (pz=pyrazolato ligand) [13],
[IrH(PCO)Cl(CO)(PCHO)] that contains the acylhy-
dride fragment and a monodentate PCHO [14] or
[NBu4]2·[Pt(C6F5)3(PCHO)] [15]. This ligand can also
behave as chelating phosphine-aldehyde with the alde-
hyde portion bonded through oxygen (s-complex) as in
RuCl2(PCHO)2 [9] or Re(Cl)(CO)3(PCHO) [16] or
through both oxygen and carbon (p-complex) as in
Co(C5Me5)(PCHO) [17] and both bonding modes are
well known for aldehyde complexes of transition metals
[18], though few rhodium aldehyde derivatives have
* Corresponding author. Tel.: +34-43-216600; fax: +34-43-
212236.
E-mail address: qppgahum@sc.ehu.es (M.A. Garralda).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01381-X

150
R. El Mail et al. / Journal of Organometallic Chemistry 648 (2002) 149–154
been reported [19]. PCHO has been widely used to
prepare hemilabile ligands, by condensation of the alde-
hyde group with primary amines, which are of interest
in the synthesis of homogeneous catalysts precursors
[20]. The condensation reaction occurs via hemiaminal
ꢂC(OH)NHR intermediates that lose water readily to
give the imine group. Some of these hemiaminals have
been detected spectroscopically and recently we have
reported that Rh(COD)(bdh)Cl (bdh, H2NNꢀC(CH3)-
C(CH3)ꢀNNH2) reacts with PCHO to give a mixture of
NMR spectrum shows only a doublet due to equivalent
phosphine groups bonded to rhodium and consequently
the resonance of the CꢃO group is a doublet of triplets.
J(Rh,C) is as expected [22] and J(P,C) is consistent
with both phosphines being cis to the carbonyl group.
In this reaction no oxidative addition of PCHO is
observed. The CO ligand strongly favours low oxida-
tion states and aldehyde CꢁH bonds are not strong
electrophiles. Other carbonylated rhodium(I) com-
pounds have been found to react with PCHO also to
give rhodium(I) species with P-monodentate PCHO
[13].
two compounds,
a hydroxyalkyl derivative [Rh-
(PCO)(PCHOH)(bdh)]+, and an acylhydride complex
[RhH(PCO)(Pbdh)]+ that also contains a stable hemi-
aminal group in a new tridentate ligand (Pbdh) formed
by reaction of aldehyde and the pendant amino group
of coordinated bdh [21]. We report now on the reaction
of [RhCl(CO)2]2 or [RhCl(COD)]2 with PCHO to give,
respectively, carbonylated Rh(I) or acylhydride Rh(III)
compounds that contain trans P-atoms. The reaction of
the Rh(III) complex with glyoxaldihydrazone (gdh) to
give selectively a stable hemiaminal containing complex
and the transformation of the hemiaminal group into
imine are also reported.
Compound 2 is stable as a solid and also in toluene
solution but decomposes readily in dichloromethane or
methanol solution and behaves as non-electrolyte in
acetone solution. Its IR spectrum shows the expected
w(RhꢁH) absorption at 2041 cm−1 and two absorptions
due to w(CꢀO) in the 1700–1600 cm−1 region, at lower
frequencies than in the free ligand, indicating acyl
coordination of PCO [5,14] and s-aldehyde coordina-
tion of PCHO [9,16,18a]. Despite considerable effort,
X-ray quality crystals of 2 could not be obtained al-
though the NMR spectra at 223 K (toluene-d8) allow its
unambiguous characterisation. The 31P{1H}-NMR
spectrum shows two doublets of doublets correspond-
ing to an AMX pattern. PCO shows the characteristic
low field resonance, ca. 55 ppm (J(Rh,P) 138 Hz) due
to the five-membered ring effect [23] the resonance of
PCHO, around 26 ppm (J(Rh,P) 137 Hz), may be
consistent with the formation of a six-membered chelate
and J(P,P) of 384 Hz, agrees with trans arrangement of
the phosphorus atoms. The 1H-NMR spectrum shows a
sharp singlet due to s-coordinated aldehyde at slightly
higher fields than in the free ligand [17,19] and the
hydride resonance in the high field region, ca. −13
ppm, shows coupling to rhodium (J(Rh,H) 28 Hz) and
to two inequivalent phosphines cis to the hydride
(J(P,H) 6 and 10 Hz). Since hydride chemical shifts are
sensitive to the nature of the trans groups [24], we
believe that in complex 2 the hydride is trans to chlo-
ride as in [RhClH2(Ph2PCH2CH2OMe)3] that shows the
hydride trans to chloride at −15.2 ppm [25]. Hydride
trans to oxygen appears around −25 ppm as in
[Rh(h2-sulfonato)H2L2] [26]. The s-aldehyde bonding
of PCHO in 2 containing two electron donating phos-
phine ligands contrasts with the p-aldehyde bonding
reported for Co(C5Me5)(PCHO) [17] and can be related
to the higher oxidation state shown by the metal in the
rhodium(III) compound [27].
2. Results and discussion
2.1. Reaction of [RhClL2]2 with PCHO (L=CO;
L2=COD)
[RhCl(CO)2]2 reacts with o-(diphenylphosphino)-
benzaldehyde (PCHO) (Rh–PCHO=1:2) in benzene to
afford a monocarbonylated rhodium(I) complex con-
taining P-monodentate PCHO, trans-[RhCl(CO)-
(PCHO)2] (1) (Scheme 1i) that shows a strong band due
to w(CꢃO) at 1971 cm−1. IR and NMR spectroscopy
confirm monodentate coordination of two equivalent
PCHO. w(CꢀO), l(H6 CO) and l(HC6 O) are almost un-
modified with respect to the free ligand. The 31P{1H}-
Warming the toluene-d8 solution results in broaden-
ing of the hydride resonance so that at room tempera-
ture an extremely broad signal is observed while neither
the aldehyde resonance nor the 31P{1H} spectrum are
modified. These observations can be explained by tran-
sient formation of a hydroxycarbene tautomer [28,29],
reductive elimination/oxidative addition of HCl or re-
Scheme 1. [RhCl(COD)]2 reacts with PCHO (Rh–PCHO=1:2) in
benzene to undergo the oxidative addition of one PCHO, with
displacement of 1,5-cyclooctadiene, and coordination of the second
PCHO molecule as P-(s-aldehyde) chelate to give [RhH-
(PCO)Cl(PCHO)] (2) as shown in (ii).

R. El Mail et al. / Journal of Organometallic Chemistry 648 (2002) 149–154
151
l31PCO and l31Pgdh (60.1 and 25.0 ppm, respectively)
and also the hydride resonance (−13.19 ppm) appear
at slightly higher field than in the related compound
derived from biacetyldihydrazone, [RhH(PCO)-
(Pbdh)]+, with methyl groups as imino C-substituents,
which shows l31PCO and l31Pbdh at 62.1 and 26.6
ppm, respectively, and l1HꢁRh at −12.86 ppm [21].
To ascertain that the selective hemiaminal formation
is a consequence of the trans-disposition of the phos-
phorus atoms in the starting material we have studied
the reaction of Rh(COD)(gdh)Cl [31] prepared ‘in situ’
with PCHO that gives a mixture of the hemiaminal-
containing species, [RhH(PCO)(Pgdh)]+ (3) and hy-
droxyalkyl derivatives [Rh(PCO)(PCHOH)(gdh)]+ (ii).
By following this reaction in CD3OD we have been able
to observe the initial formation of 3, and two hydrox-
yalkyl intermediates 4 and 5 containing cis phosphorus
atoms. Compound 4 contains P of the acylphosphine
chelate trans to N and P of the PCHOH chelate trans
to acyl (lP
6
CO 57.6 {dd} ppm, J(Rh,P) 150, J(P,P) 21
OH
Hz; lPCHOH 37.1 {dd} ppm, J(Rh,P) 82 Hz; lCH
6
6
6.03 {s} ppm) while 5 contains P of the PCHOH
chelate trans to N and P of the acylphosphine chelate
Scheme 2.
trans to hydroxyalkyl (lP
6 CO 38.3 {dd} ppm, J(Rh,P)
85, J(P,P) 19 Hz; lPCHOH 60.2 {dd} ppm, J(Rh,P)
6
ductive elimination/oxidative addition involving the
acylhydride fragment occurring faster than 31P relax-
ation. We were unable to observe any resonance at
lower field due to the hydroxycarbene proton in the
223–293 K range. Upon addition of Et3N to a toluene-
d8 solution of 2 at 223 K the complex remains unaltered
though on raising the temperature the hydride reso-
nance disappears and a complex mixture of unidentified
species is formed. Therefore, we believe that the broad-
ening of the hydride resonance is due to a fast reductive
elimination/oxidative addition of HCl.
153 Hz). Compounds 4 and 5 rearrange with time into
the trans derivative 6. By using dichloromethane or
methanol as solvents, complexes 3 and 6 can be sepa-
rated from the reaction mixtures, [RhH(PCO)(Pgdh)]Cl
precipitates when the reaction is performed in CH2Cl2
while [Rh(PCO)(PCHOH)(gdh)]Cl is only partially sol-
uble in MeOH.
Compound 6 has been fully characterised as the
tetraphenylborate salt [Rh(PCO)(PCHOH)(gdh)]BPh4.
It behaves as 1:1 electrolyte in acetone solution and
1
shows w(OH) around 3500 cm−1. H-NMR confirms
the formation of the hydroxyalkyl group bonded to
rhodium [32]. The dihydrazone ligand shows two sets of
resonances due to inequivalent imino fragments and the
31P{1H}-NMR spectrum shows two doublets of dou-
blets (ABX pattern) corresponding to two inequivalent
phosphines mutually trans (J(P,P) 320 Hz).
The uncoordinated HNꢁCH(OH) hemiaminal group
in [RhH(PCO)(Pgdh)]+ 3, being included in a rather
rigid seven-membered metallocycle, fails to undergo
easily the condensation reaction to give the imine,
hydrogen transfer from N to O to allow water elimina-
tion needs both H and OH being on the same side of
the NꢁC bond [33]. Compound 3 is stable in the solid
state and also in unstabilized chloroform for long peri-
ods, over 15 days. This was unexpected, because, re-
lated [RhH(PCO)(Pbdh)]+, containing methyl groups
as imino C-substituents undergoes the condensation
reaction at room temperature in unstabilized chloro-
form, though slowly [21] and suggests that when the
2.2. Hemiaminal formation
[RhH(PCO)Cl(PCHO)] (2), which contains trans
phosphine groups, reacts in benzene with gdh,
H2NNꢀCHCHꢀNNH2 (gdh) to give species 3 as a
unique reaction product (Scheme 2i). The diimine dis-
places both chloride and s-aldehyde which reacts with
the pendant amino group of the dihydrazone to form a
hemiaminal group and the new tridentate ligand Pgdh.
[RhH(PCO)(Pgdh)]+ (3) has been fully characterised as
the tetraphenylborate salt (see Section 3), behaves as
1:1 electrolyte in acetone solution [30] and its FAB
spectrum shows the corresponding [M+] peak. The
appearance of w(OH) at ca. 3500 cm−1 and the reso-
nances at 2.16 (s, OH), 5.09 (d, NH) and 6.78 (d, CH)
ppm indicate the hemiaminal formation and the
31P{1H}-NMR spectrum shows an AMX pattern with
trans arrangement of the phosphorus atoms. In 3 both

152
R. El Mail et al. / Journal of Organometallic Chemistry 648 (2002) 149–154
hemiaminal group derived from acetyl, into 9a (l31PCO
62.5 {dd} J(Rh,P) 126, J(P,P) 306; l31Papvdh 32.9
{dd} J(Rh,P) 119) while isomer 8b remains unmodified
(Scheme 3). This observation confirms that the conden-
sation reaction of hemiaminals included in seven-mem-
bered metallocycles to form azines is favoured by the
presence of methyl substituents in the imino fragment.
It has been reported that by increasing the number of
methyl groups as C-substituents in coordinated dihy-
drazones, the intraligand repulsion effects also increase
[31,34], therefore we think that the presence of the
methyl group makes the seven-membered ring to adopt
a more suitable conformation to favour the hydrogen
transfer from N to O and hence the condensation
reaction.
fragment RCꢀNꢁNHꢁCH(OH) contains R: CH3 the
azine formation reaction is easier. The condensation
reaction in 3 occurs upon addition of HCOOH that
traps the released water, thus shifting the equilibrium to
the imine, and forms [RhH(PCO)(Pagdh)]+ 7 (Scheme
3), though the obtained compound is impure. The
hydride and the P-resonances of 3 disappear while new
signals due to 7 appear (l1HꢁRh −12.82 {ddd}
J(Rh,H) 20, J(PCO,H) 12, J(Pagdh,H) 8; l31PCO 58.8
{dd} J(Rh,P) 126, J(P,P) 297; l31Pagdh 34.4 {dd}
J(Rh,P) 117). The shift towards lower fields of the
P-resonance of the tridentate ligand on going from 3 to
7 suggests that 7 also contains a tridentate ligand
forming a seven-membered PN [23] and a five-mem-
bered NN chelate ring.
To confirm the influence of the imino C-substituents
in the azine formation reaction, we have prepared a
hemiaminal containing complex using pyruvaldihydra-
zone, H2NNꢀCHC(CH3)ꢀNNH2 (pvdh). The reaction
of Rh(COD)(pvdh)Cl [31], prepared ‘in situ’ in
dichloromethane, with PCHO gives a precipitate of
[RhH(PCO)(Ppvdh)]Cl. The complex has been charac-
terised as the tetraphenylborate salt (8) and is a mixture
of two isomers due to hemiaminal formation using the
ꢁC(CH3)ꢀNNH2 fragment, 8a, or the ꢁCHꢀNNH2 frag-
ment, 8b (see Scheme 3). The NMR spectra show the
presence of both isomers in ca. 1/2 ratio, two hydride
resonances and four doublets of doublets in the
31P{1H}-NMR are observed. Due to the sensitivity of
the hydride chemical shifts to the nature of the trans
groups [24], we assign the resonance at lower field to
the more abundant isomer 8b. We find now that
l31PCO appears to be sensitive to the nature of the
imino group trans to the acyl group, so that the pres-
ence of methyl C-substituents makes the corresponding
resonance to appear at slightly lower fields,
l31PCO(8a)\l31PCO(8b). The dissolution of 8 in un-
stabilized choroform, in the absence of HCOOH, leads
to the slow transformation of isomer 8a, containing the
3. Experimental
The preparation of the metal complexes was carried
out at room temperature (r.t.) under nitrogen by stan-
dard
Schlenk
techniques.
[RhCl(COD)]2
and
[RhCl(CO)2]2 [35] were prepared as previously reported.
a-Diimines [34,36] were synthesised according to known
procedures.
(PCHO) was purchased from Aldrich and used as re-
ceived. Microanalysis were carried out with a Leco
CHNS-932 microanalyser. Conductivities were mea-
sured in acetone solution with a Metrohm E 518 con-
ductimeter. IR spectra were recorded with a Nicolet
FTIR 740 spectrophotometer in the range 4000–50
cm−1 using KBr pellets or nujol mulls. NMR spectra
o-(Diphenylphosphino)benzaldehyde
1
were recorded with an XL-300 Varian spectrometer, H
and 13C (TMS internal standard) and 31P (H3PO4 exter-
nal standard) spectra were measured from CDCl3 or
toluene-d8 solutions. Mass spectra were recorded on a
VG Autospec, by liquid secondary ion (LSI) MS using
nitrobenzyl alcohol as matrix and a cesium gun (Uni-
versidad de Zaragoza).
3.1. trans-[RhCl(CO)(PCHO)2] (1)
To a benzene solution of [RhCl(CO)2]2 (0.06 mmol)
was added an stoichiometric amount (0.24 mmol) of
PCHO whereupon evolution of gas is observed and
precipitation of a yellow solid occurs which was filtered
off, washed with benzene and vacuum-dried. Yield:
45%. IR (cm−1): 1971(s), w(CꢃO); 1689(s), w(CꢀO);
281(m), w(RhꢁCl). 1H-NMR (CDCl3): l 11.07 (s,
CHO). 13C{1H}-NMR (CDCl3): l 187.3 (dt, CꢃO),
J(Rh,C) 73, J(P,C) 15; 190.3 (t, CHO), J(P,C) 6,
J(Rh,C) 6. 31P{1H}-NMR (CDCl3): l 28.9 (d), J(Rh,P)
127. Anal. Calc. for C39H30ClO3P2Rh: C, 62.71; H,
4.05. Found: C, 62.59; H, 4.06%.
Scheme 3.

R. El Mail et al. / Journal of Organometallic Chemistry 648 (2002) 149–154
153
1
3.2. [RhH(PCO)Cl(PCHO)] (2)
769 [M+]. H-NMR (CDCl3): l 5.08 (ddd, HCꢁOH),
3J(H,H) 4, J(Rh,H) 2, J(P,H) 16; 5.91 (s), 5.23 (s)
(NH2); 1.49 (d, OH); 5.99 (s), 5.94 (s) (HCꢀN).
31P{1H}-NMR (CDCl3): l 55.1 (dd, PA), J(Rh,P) 132,
J(P,P) 316; 45.8 (dd, PB), J(Rh,P) 130. Anal. Calc. for
C64H56BN4O2P2Rh: C, 70.60; H, 5.18; N, 5.15. Found:
C, 70.23; H, 4.90; N, 5.10%.
2
4
To a benzene solution of [RhCl(COD)]2 (0.06 mmol)
was added an stoichiometric amount (0.24 mmol) of
PCHO. Addition of diethyl ether gave a yellow precipi-
tate, which was filtered off, washed with diethyl ether
and vacuum-dried. Yield: 68%. IR (cm−1): 2041(m),
w(RhH); 1664(s), 1634(s), w(CꢀO); 273(w), w(RhꢁCl).
FABMS: Calc. for C38H30ClO2P1203Rh: 718; observed:
3.5. [RhH(PCO)(Pp6dh)]BPh4 (8)
1
683 [M+ꢁCl]. H-NMR (toluene-d8, 223 K): l −12.98
(ddd, HRh), J(Rh,H) 28, J(P,H) 10, 6; 8.98 (s, CHO).
31P{1H}-NMR (toluene-d8): l 55.3 (dd, PCO), J(Rh,P)
138, J(P,P) 384; 26.2 (dd, PCHO), J(Rh,P) 137. Anal.
Calc. for C38H30ClO2P2Rh: C, 63.48; H, 4.21. Found:
C, 63.19; H, 4.22%.
To a CH2Cl2 solution of [RhCl(COD)]2 (0.04 mmol)
was added an stoichiometric amount (0.08 mmol) of
pvdh whereupon a red precipitate was formed that
upon addition of PCHO (0.16 mmol) gave a yellow
solution from which a yellow precipitate of [RhH-
(PCO)(Ppvdh)]Cl appear which was filtered off and
dried (50% yield). To a MeOH solution of [RhH-
(PCO)(Ppvdh)]Cl (0.06 mmol) was added NaBPh4 (0.06
mmol) to give a precipitate which was filtered off,
washed with MeOH and vacuum-dried. Yield: 70%. IR
(KBr, cm−1): 3525(br), w(OH); 3387(m), 3302(w),
3225(w) w(NH2); 2048(w), w(RhH); 1612(s), w(CꢀO);
1576(s), w(CꢀN). \M (V−1 cm2 mol−1): 96 (acetone).
FABMS: Calc. for C41H38N4O2P1203Rh: 783; observed:
783 [M+]. 1H-NMR (CDCl3): l −13.24 (m, HRh),
3.3. [RhH(PCO)(Pgdh)]BPh4 (3)
To an orange benzene solution of [RhCl(COD)]2
(0.04 mmol) was added an stoichiometric amount of
PCHO (0.16 mmol) to obtain a yellow solution. Addi-
tion of gdh (0.08 mmol) and stirring for 45 min gave a
yellow precipitate of [RhH(PCO)(Pgdh)]Cl which was
filtered off and dried (75% yield). This solid (0.06
mmol) was dissolved in MeOH and NaBPh4 (0.06
mmol) was added to give a precipitate, which was
filtered off, washed with MeOH and vacuum-dried.
Yield: 53%. IR (KBr, cm−1): 3485(br), w(OH);
3429(m), 3281(m), w(NH2); 2049(w), w(RhH); 1605(s),
w(CꢀO); 1577(s), w(CꢀN). \M (V−1 cm2 mol−1): 79
(acetone). FABMS: Calc. for C40H36N4O2P1203Rh: 769;
3
J(Rh,H) 20, J(P,H) 10; 5.07 (d, NH), J(H,H) 9; 4.92
(s, NH2); 5.46 (s) (HCꢀN); 0.94 (s, CH3) for 8a;
−13.02 (m, HRh), J(Rh,H) 20, J(P,H) 10; 5.25 (d,
3
NH), J(H,H) 9; 4.47 (s, NH2); 2.07 (s, OH); 4.86 (s)
(HCꢀN); 0.84 (s, CH3) for 8b. 31P{1H}-NMR (CDCl3):
l 61.5 (dd, PCO), J(Rh,P) 128, J(P,P) 309; 25.1 (dd,
PNN), J(Rh,P) 121 for 8a; 60.0 (dd, PCO), J(Rh,P)
126, J(P,P) 307; 26.1 (dd, PNN), J(Rh,P) 119 for 8b.
Anal. Calc. for C65H58BN4O2P2Rh: C, 70.79; H, 5.30;
N, 5.08. Found: C, 70.37; H, 5.56; N, 4.83%.
1
observed: 769 [M+] H-NMR (CDCl3): l −13.19 (m,
HRh), J(Rh,H) 20, J(P,H) 10; 6.78 (d, HCꢁN),
3J(H,H) 10; 5.09 (d, NH); 4.85 (s, NH2); 2.16 (s, OH);
5.21 (s), 4.76 (s) (HCꢀN). 31P{1H}-NMR (CDCl2): l
60.1 (dd, PCO), J(Rh,P) 126, J(P,P) 304; 25.0 (dd,
PNN), J(Rh,P) 120. 13C{1H}-NMR (CDCl3): l 238.0
(d, CO), J(Rh,C) 31; 141.3 (s), 139.1 (s) (CꢀN); 84.3 (d,
COH), J(P,C) 6. Anal. Calc. for C64H56BN4O2P2Rh: C,
70.60; H, 5.18; N, 5.15. Found: C, 70.20; H, 5.32; N,
5.12%.
Acknowledgements
Partial financial supports by UPV and Diputacio´n
Foral de Guipuzcoa are gratefully acknowledged.
3.4. [Rh(PCO)(PCHOH)(gdh)]BPh4 (6)
To a MeOH suspension of [RhCl(COD)]2 (0.12
mmol) were added stoichiometric amounts of gdh (0.24
mmol) and PCHO (0.48 mmol). Stirring for 3h at r.t.
gave a yellow precipitate of [Rh(PCO)(PCHOH)-
(gdh)]Cl which was filtered and dried (25% yield). 0.05
mmol of this product were dissolved in MeOH, upon
addition of NaBPh4 (0.05 mmol) a yellow precipitate
was formed, which was filtered off, washed with MeOH
and vacuum-dried. IR (KBr, cm−1): 3521(m), w(OH);
3380(m), 3288(m), 3260(m), w(NH2); 1612(s), w(CꢀO);
1577(s), w(CꢀN). \M (V−1 cm2 mol−1): 116 (acetone).
FABMS: Calc. for C40H36N4O2P1203Rh: 769; observed:
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